Antenna drive mechanism



Sept. 20, 1966 M. P. GEORGE 3,273,813

ANTENNA DRIVE MECHANI SM Filed Dec. 22, 1964 2 Sheets-Sheet 1 ATTORNEYS Sept. 20, 1966 M. P. GEORGE ANTENNA DRIVE MECHANISM 2 Sheets-Sheet 2 Filed Dec. 22, 1964 mm m mm 0 W 1 L ,m m M M W I 5% United States Patent Ofifice 3,273,813 Patented Sept. 20, 1966 3,273,813 ANTENNA DRIVE MECHANISM Michael P. George, 161 Concord Ave., Lexington, Mass. Filed Dec. 22, 1964, Ser. No. 420,397 6 Claims. (Cl. 24254) This invention relates generally to power drive mechanisms for telescopic antennas and more particularly is directed towards a new and improved power drive unit for extending and retracting telescopic radio antennas of the type used on automobiles for mobile transmitters and receivers.

There is a wide variety of power drive units available for extending and retracting telescopic radio antennas of the sort used on automobiles and the like. Most of the units available currently are unsatisfactory for one reason or another and one of the primary objections to most units of this sort is their relatively high cost which is necessitated by reason of the complexity of the mechanism. Many drive units now in use employ a flexible rod which extends up through the center of the antenna and is attached to the topmost section. A winding mechanism is attached to the lower end of the flexible rod and mounted to the base of the antenna. A conventional reversible motor, is employed to wind and unwind the flexible rod so as to extend or retract the antenna as desired.

Because most of these mechanisms employ some sort of a helical winding arrangement rather complex guiding elements are required to properly wind and unwind the rod and prevent jamming. Furthermore, most of these units employ frictional gripping elements which grab the rod to drive it one direction or the other. These gripping elements are normally of a sharp or rough character and abrade the surface of the flexible rod which customarily is of nylon. As a result, the rod is subjected to heavy wear which greatly reduces the life span of the unit.

Accordingly, it is an object of the present invention to provide improvements in power drive mechanisms for use particularly with telescopic radio antennas.

Another object of this invention is to provide a novel mechanism for winding and unwinding a flexible rod.

A further object of this invention is to provide a novel clutch mechanism for a power driven rotary unit.

More particularly, this invention features a drive unit for a telescopic antenna having a flexible rod extending there through comprising a power-driven rotatable member having a relatively deep annular groove about its periphery in which the rod is wound. A pair of oppositely facing resilient O-ring are mounted near the periphery of the groove, normally closing the outer portion of the groove and between which the rod is fed for winding and unwinding. A housing, enclosing the rotatable member, is mounted on the lower end of the antenna and is provided with a guide for directing the rod from the antenna into the groove between the O-n'ngs. Rotation of the rotatable member in one direction or the other is operative to wind the flexible rod to retract the antenna or to unwind the rod and extend the antenna, the function of the O-rings being to trap the coiled portion of the rod within the groove whereby a longitudinal force may be applied to the rod by rotation of the rotatable member.

As another feature of this invention, a simple clutch mechanism is mounted between the driving mechanism and the rotatable member. This clutch mechanism comprises a bar fixed to the driving member and provided with spring loaded elements at its outer ends for engaging detents fixed to the rotatable member.

However, these and other features of the invention,

along with further objects and advantages thereof, will become more fully apparent from the following detailed description of a preferred embodiment of the invention, with reference being made to the accompanying drawings in which:

FIG. 1 is a view in perspective of an antenna drive mechanism made according to the invention,

FIG. 2 is another view in perspective showing the mechanism from the side opposite that shown in FIG. 1,

FIG. 3 is a view in side elevation partly in section of the mechanism,

FIG. 4 is a view similar to FIG. 3 but partly exploded,

FIG. 5 is a cross-sectional view taken along the line 5-5 of FIG. 3, and,

FIG. 6 is a cross-sectional view taken along the line 6--6 of FIG. 3.

Referring now to the drawings, the reference character it generally indicates a housing having a primarily circular configuration but with one quadrant extending out to form a right angular block portion 12. As shown in FIG. 5, the quadrant portion 12 is formed with a verti cal passage 14 through which extends a flexible rod 16 of nylon, or the like, and having its upper end attached to the upper section of a telescopic antenna (not shown). In practice, a bushing 18 preferably of Teflon or similar material is set into the passage 14 to provide a smooth sliding drag movement for the nylon rod 16 which moves in and out of the passage 14.

As shown in FIGS. 2, 3 and 4, a reversible motor 20 and a reduction gear 22 assembled, as a unit are mounted, to one side of the housing 10. A drive shaft 24, extends out of the gear box 22 through an opening formed in a sidewall 26 of the housing.

The housing itself typically is in two-parts comprising the annular wall 26 and a main body portion 28 in which is formed a cylindrical recess or chamber 30 normally closed by the wall 26 attached by radial screws 31.

Within the cylindrical chamber there is rotatably mounted a pulley-like assembly 32 comprising two annular discs or plates 34 and 36 connected in coaxial relation by screws 38. As shown in FIGS. 4 and 5, the plate 34 is of circular configuration having an annular groove 40 formed near its outer periphery in its right-hand face as viewed in FIG. 4 to accommodate an O-ring 42 made of rubber or other resilient material. The plate 34 is also formed with an annular shoulder 44 concentric with a central opening 46. Extending concentrically about a substantial portion of the shoulder 44 is a wall 48 which is open over an arc of about 60. The wall 48 thus forms with the shoulder 44 an annular groove Stl in which the free end of the nylon rod 16 is laid. The rod 16 is sufliciently rigid and the tolerances of the groove 50 sufliciently close that the rod will be connected tightly to the assembly 32 without any further securing means other than the rod end being laid in the groove and wound about it with one end passing out through the wall opening.

The opposing plate 36 is of substantially the same diameter as the plate 34 and is also formed with an opposing annular groove 52 to receive another O-ring 54 corresponding in size and shape to the O-ring 42. The plate 36 is formed with an integral hub 56 which fits snugly within the opening 46 formed in the plate 34. Tapped openings 58 receive the threaded ends of the screws 38 for assembling the two plates together. When the two plates are assembled as shown in FIG. 3, the two O-rings 42 and 54 are mounted oppositely one another and bear rather lightly against one another about their opposing edges. The two plates, by reason of the shoulder 44, define a deeply recessed annular groove 60 in which the flexible rod 16 is wound in a flat spiral. As shown in FIG. 5 the flexible rod is passed between the O-rings 42 and r, 2) 54 out through the passage 14. The function of the rings, therefore, is to trap the outer loop of the coiled rod within the groove 60 when the unit is unwinding the rod. It will be understood that when the pulley-like assembly 32 rotates in a clockwise direction as viewed in FIG. 5, the rod will start to uncoil so that the outermost loop will flex out and press outwardly against the O-rings. This will provide longitudinal thrust on the rod so that rotation of the pulley assembly will force the straight portion of the rod out between the O-rings and through the opening 14 thus extending the antenna. When retracting the antenna, the motor driving the pulley assembly is merely reversed and the rod is drawn down through the opening and wound about the rod 48 in a flat spiral.

With this arrangement, no rod gripping mechanism is required and there is substantially no wear whatsoever on the rod either when winding or unwinding since the entire push on the rod is provided by the O-rings trapping a coiled section of the rod within the pulley groove 60 to exert a longitudinal thrust on the rod.

Connecting the motor and reduction gear to the pulley assembly is a clutch mechanism adapted to slip in the event of an overload. This clutch mechanism comprises a bar 62 (FIG. 6) and drivingly connected to the shaft 24 by means of a set pin 64 extending through the bar 62 and bearing against a flat face formed on the drive shaft. The bar also has a central hub 66 rotatably received in an opening 68 formed in the hub 56 of the plate 36. Washers 70 and 72 are provided on either side of the bar 62.

The outer ends of the bar are formed with recesses '74 in each of which is mounted a coil spring '76 and a bearing ball 78. The ball, in practice, is trapped between the outer end of the spring 76 and a cylindrical wall 80 formed by a circular recess in the right-hand side of the plate 36 as viewed in FIG. 4. Detent stop members 82, in the form of rivets, are set in openings 84 formed in the wall 80, 180 apart as best shown in FIG. 6.

With this arrangement, it will be understood that a torque applied to the bar by the motor will cause the outer ends to engage the detent stops 82 and thereby cause the pulley assembly 32 to rotate in whatever direction the torque is applied. In the event of overload, the springloaded balls 178 will merely override the stops 82 so as not to damage either the motor, the gear or the pulley assembly.

The mechanism illustrated and described herein is mechanically simple having a minimum number of parts and may be readily fabricated with conventional machinery. No unusual machiningor casting techniques are required to fabricate the mechanism so that it may be produced at a low cost. The unit has the further advantage of winding and unwinding the flexible rod without abrading its surface in any way so that there is substantially no wear on the rod during operation.

While the invention has been described with particular reference to the illustrated embodiment, it will be understood that numerous modifications thereto will appear to those skilled in the art. Accordingly, the above description and accompanying drawings should be taken as illustrative of the invention and not in a limiting sense.

Having thus described the invention, what I claim and desire to obtain by Letters Patent 0f the United States is:

1. A power drive mechanism for a telescopic antenna, comprising (a) a pulley formed with a peripheral groove,

(b) power means for selectively rotating said pulley in either of two rotary directions,

(c) a pair of resilient annular members mounted to said pulley in registered opposition adjacent the opening of said groove to restrict the size of said opening,

(d) a housing enclosing said pulley and having an opening formed therein generally tangential to said pulley, and

(e) a flexible rod extending through said housing and having one end connected to said antenna and the other end secured to said pulley, said rod having a diameter larger than the restricted groove opening.

2. A power drive mechanism according to claim 1 including a bushing mounted in said housing opening, said bushing being formed with an orifice of substantially the same diameter as said rod.

3. A power drive mechanism according to claim 1 including clutch means drivingly connected between said power means and said pulley.

4. A power drive mechanism for a telescopic antenna, comprising (a) a pulley formed with a peripheral groove,

(b) power means for selectively rotating said pulley in either of two rotary directions,

(c) a pair of resilient annular members mounted, concentrically to said pulley in registered opposition on each side of said groove adjacent the peripheral opening of said groove to restrict the size of said opening,

((1) a housing enclosing said pulley and having an opening formed therein generally tangential to said pulley, and

(e) a flexible rod extending through said housing opening and having one end secured to said pulley,

(f) said pulley groove being of a uniform width generally corresponding to the diameter of said rod whereby said rod will form a fiat spiral when wound about said pulley.

5. A power drive mechanism accordingly to claim 4 including an overload release clutch operatively connected between said pulley and said power means.

6. A power drive mechanism according to claim 5 wherein said clutch comprises a radially extending member fixed to said power means, a cylindrical wall fixed to said pulley and concentric with said member, said wall disposed in radial spaced relation to the periphery of said member, stop means mounted to said wall and resilient means mounted in the periphery of said member normally engaging said stop means in driving relation and adapted to override said stop means when said pulley is overloaded.

References Cited by the Examiner UNITED STATES PATENTS 4/1954 Landenberger et al. 24254 7/1959 Ulrich 24254 

1. A POWER DRIVE MECHANISM FOR A TELESCOPIC ANTENNA, COMPRISING (A) A PULLEY FORMED WITH A PERIPHERAL GROOVE, (B) POWER MEANS FOR SELECTIVELY ROTATING SAID PULLEY IN EITHER OF TWO ROTARY DIRECTIONS, (C) A PAIR OF RESILIENT ANNULAR MEMBERS MOUNTED TO SAID PULLEY IN REGISTERED OPPOSITION ADJACENT THE OPENING OF SAID GROOVE TO RESTRICT THE SIZE OF SAID OPENING, (D) A HOUSING ENCLOSING SAID PULLEY AND HAVING AN OPENING FORMED THEREIN GENERALLY TANGENTIAL TO SAID PULLEY, AND (E) A FLEXIBLE ROD EXTENDING THROUGH SAID HOUSING AND HAVING ONE END CONNECTED TO SAID ANTENNA AND THE OTHER END SECURED TO SAID PULLEY, SAID ROD HAVING A DIAMETER LARGER THAN THE RESTRICTED GROOVE OPENING. 